Treating water-wetted surfaces with corrosion-resistant coating material



Dec. 1, 1964 R. M. JORDA 3,159,499

TREATING WATER-WETTED SURFACES WITH CORROSION-RESISTANT COATINGMATERIALFiled Sept. 21, 1961 PO LYAMIDE POLYEPOXIDE FILLER PIGMENT PIG MENTFILLERS 5% lo 50% sroiehiomerric excess of polyomide in relation topolyepoxide Mix thoroughly at ambient temperature PUTTY- LIKE TREATINGCOMPOSIT|ON Application to surfaces immersed in water INVENTOR:

ROBERT M. JORDA HIS AGENT United States Patent 3,159,499 TREATXNGWATER-WETTED SURFAfiES WETH CQRRUSltlN-RESISTANT COATENG MATEREAL RobertM. .lorda, Houston, Tex., assignor to Shell Gil Company, New York, N.Y.,a corporation of Delaware Filed Sept. 21, 1961, Ser. No. 139,605 14-Qlaims. (Cl. 117-4) This invention relates to a new process for treatingwet surfaces and to the resulting products. More particularly, theinvention relates to a new process for treating Water Wetted surfaces toapply a corrosion-resistant coating thereto and/ or repair defects inthe said surfaces, and to the products prepared thereby.

Specifically, the invention. provides a new and highly efiicient processfor applying a hard, tough and highly flexible resinous material towater wetted surfaces, and preferably metal surfaces, which materialprovides protection against corrosion and/or repairs defects so as torender the surface water tight. This process comprises applying to thewater wetted surface a composition comprising a mixture of apolyepoxi'de having more than one Vic-epoxy group, and preferably aglycidyl polyether of a polyhydric phenol, and a special controlledexcess amount of a polyamide of an aliphatic or cycloaliphaticpolycarboxylic acid containing at least 7 carbon atoms and an aliphaticpolyamine, said polyamide containing groups reactive with the epoxygroups, and allowing the composition to set hard.

As a special embodiment, the invention provides a new process forapplying a hard, tough and highly flexible corrosion-resistant coatingto metal surfaces of off-shore structures which are in the vicinity ofthe water line and may be highly corroded, such as, for example, metalsupports of off-shore drilling platforms, which comprises forming aputty-like mixture of a polyepoxide, 5% to 50% stoichiometric excess ofa polyamide of a polymerized unsaturated long chain fatty acid and analiphatic polyamine, said polyamide having a plurality of free aminohydrogen, and a thixotropic material, and then applying the putty-likematerial to the surface while submerged below the water, and allowingthe coating to set hard while under the surface of the water.

This application is a continuation-in-part of my application Serial No.61,063, filed October 7, 1960, now abandoned.

There is a growing need in industry for a superior plastic coatingmaterial that can be applied to surfaces while wet or while submergedunder water so as to repair defects therein and/ or apply acorrosion-resistant coating thereto. This includes, for example, repairof leaks in water lines without interruption of the water flow, repairof electrical conduits buried in wet soil, repair of boat hulls whilethe boat is still in the Water, repair of waterwetted surfaces ofpressure vessels, and the like, as well as applying corrosion-resistantcoatings to the aforedescribed materials.

One of the greatest problems has been the prevention of corrosion ofmetal members of off-shore drilling structures,particularly those partsdisposed in the splash zone, i.e., disposed in the vicinity of the Waterline. The corrosion of metal members in this area is particularlysevere. If a metal member extends from the bottom to a point above thewater level, the general pattern of its relative losses of metal due tocorrosion usually has the following general characteristics; thecorrosion rate is relatively low along those portions of the metalmember which is within and immediately above the bottom sediments inwhich the member is disposed. Proceeding upwardly through the zonebetween the mud line and the low-tide water level, the rate of corrosionundergoes arelatively sudden and severe increase along a portion of themetal 3,159,499 Patented Dec. 1, 1964 member which is located just belowthe low-tide water level and is generally continuously submerged.Further up, the corrosion rate may drop off along a short sectionbetween the low-tide and high-tide water levels, and then increase to arate which usually exceeds the corrosion rate anywhere else along themetal member, this maximum being within the zone in which the member issubject to the action of waves. Above this zone, the metal member issubjected to atmospheric corrosion in which the metal is in contact withthe moist air and some spray action normally existing above a body ofwater. The corrosion rate is high, and corrosion protection is neededalong all of the portions of such metal members which are wetted andexposed to relatively high oxygen concentrations. Such portions includethose portions of the metal which are substantially continuouslyimmersed in water which has a relatively high concentration of dissolvedand/ or entrained oxygen.

It is known that those portions of metal members which are located wellabove the water line may be adequately protected against corrosion bythe application thereto of conventional marine paints. Similarly, theuse of impressed cathodic as well as of sacrificial anodic protectiontechniques have been found to provide adequate protection of thecorrodible metal members located well below the water line. However,several factors make it exceedingly diflicult to protect those portionsof corrodible metal members which are located in the vicinity of thewater line. This is a zone in which waves and tides produce ratherstrong currents which cause rapid erosion of most non-metallic coatingsnormally applied to the metal surfaces. It is essential that corrosionprotective materials be applied to those portions of the corrodiblemetal members which extend at least about a foot, or frequently evenfurther below the low-tide level. The problem of applying suchproduction to metal member portions which are located under water isfurther aggravated by the presence of cross-bracing at or very close tothe water line.

It was previously demonstrated that some simple offshore structures,e.g., wellheads mounted on unbraced surface conductors, may be protectedagainst corrosion by enclosing the underwater portions thereof which arenear the Water line by means of a caisson-type structure, removing thewat'er from the caisson-type structure, and then applying a plasticcoating by any of the well-known conventional marine coating applicationprocedures. Although the cost of the materials which are used in thiscaisson technique is quite low, the use of this technique is ratherexpensive due primarily to the time necessary for effecting saidcorrosion inhibition technique. Also, the application 'of this techniquebecomes unfeasible, complex and diflicult when the structure to be thusprotected has cross-bracing and the like at or near the water line,e.g., where the aforesaid corrosion protection is to be applied.

Similar disadvantages are inherent in other more recently proposedtreatment processes, such as, surrounding the corrodible metal memberswith a corrosion-resistant sleeve, then removing the water between themember to be protected and the sleeve, and finally filling the void thusformed with a corrosion-resistant sealing material construction orcoating the structural members which are to be disposed at or near thewater line with corrosionresistant metals or plastics; or placing asleeve around the metal member, which sleeve is filled with porousmaterials which keep the metal members continuously wetted with anelectrolyte, and effecting corrosion inhibition by means of asacrificial metal and anoicl arrangement.

It is an object of the invention therefore to provide a: new process fortreating wet surfaces- It is a further object to provide a new low-costprocess for applying a corrosion-resistant coating to a water wettedsurface. It is a further object to provide a new process for applying acorrosion-resistant coating to already corroded metal surfaces whileimmersed in water. It is a further object to provide a new process forapplying a coating to wet surfaces which render the surfaces resistantto corrosion by fresh or saline water. It is a further object to providean easy method for applying a protective coating to complicatedstructural members of off-shore drilling platforms which are disposed inthe vicinity of the water line. It is a further object to provide a newprocess for applying a coating which is hard and tough to wet surfaces.It is a further object to provide a new process for applyingcorrosion-resistant coatings which have excellent flexibility anddistensibility. It is a further object to provide an economical andhighly efficient process for treating surfaces which are under saltwater, It is a further object to provide a new process for treating wetsurfaces to repair defects therein. It is a further object to provide anew process for treating wet surfaces to make them water tight andcorrosion resistant. These and other objects of the invention will beapparent from the following detailed description thereof and from theattached drawing which is a flow diagram illustrating one preferredmethod of preparing the new compositions and using the compositions fortreating surfaces in contact with water.

It has now been discovered that these and other objects may beaccomplished by the process of the invention which comprises applying tothe water wetted surface a composition comprising a mixture of apolyepoxide having more than one Vic-epoxy and preferably a glycidylpolyether of a polyhydric phenol, and a special controlled excess amountof a polyamide of an aliphatic or cycloaliphatic polycarboxylic acidcontaining at least 7 carbon atoms and an aliphatic polyamine, saidpolyamide containing groups reactive with the epoxy groups, and allowingthe composition to set hard. It has been found that by the use of thisprocess one can very easily apply corrosion-resistant coatings tosurfaces which are wet or even totally submerged under water. Theapplication is particularly efficient when applied as a putty tosurfaces while they are under water. The coatings have excellentadhesion to the surface even when they are under water. The coatingswhen cured also demonstrate outstanding resistance to corrosion by freshwater, saline water, moist air and the like. In addition, the coatingsare very hard and tough and have excellent flexibility anddistensibility. They thus can be subjected to considerable pressureswithout chipping or cracking.

It has also been surprisingly found that the process is effective forrepairing defects in wet surfaces, such as holes, cracks, pits and thelike. When the compositions are applied to the surfaces when wet orsubmerged under water, the coatings fill the holes or cracks and can beleveled to form a smooth coating. The process can thus be used both forrepair and for application of corrosion resistant coatings to boathulls, water pipes, electrical conduits, pilings and the like.

The theory which was developed for the obtaining of the above-describedsuperior results has been confirmed by laboratory tests. The use of thecontrolled excess amount of the polyamide as described hereinafterbrings about a displacement of the water molecules at the interface ofthe surface and coating composition and permits the formation at thatpoint of the superior adhesive forces which bond the cured compositionto the surface. The afiinity of the polyamide to the metal or othersurface is greater than the affinity of water to such surfaces and thus,the polyamide displaces the water to provide an essentially water-freesurface onto which the coating can bond. It has been shown that only ifthe polyamide is available as an excess over the stoichiomctric amountwill the drying of the surfaces occur.

The polyepoxides used in the process of the invention comprise thoseorganic materials possessing more than one Vic-epoxy group, i.e., morethan one group. These materials may be saturated or unsaturated,aliphatic, cycloaliphatic, aromatic or heterocyclic and may be situatedwith substituents, such as chlorine, hydroxyl groups and ether radicals.They should not, however, possess active groups, such as isocyanategroups, which are reactive with water.

For clarity, many of the polyepoxides and particularly those of thepolymeric type will be described in terms of epoxy equivalent value. Themeaning of this expression is described in US. 2,633,458.

If the polyepoxide consists of a single compound and all of the epoxygroups are intact, the epoxy equivalency will be integers, such as 2, 3,4 and the like. However, in the case of polymeric type polyepoxides manyof the materials may contain some of the monomeric monoepoxides or havesome of their epoxy groups hydrated or otherwise reacted and/or containmacromolecules of somewhat different molecular weight so the epoxyequivalent values may be quite low and contain fractional values. Thepolymeric material, may, for example, have epoxy equivalent values, suchas 1.5, 1.8, 2.5 and the like.

Examples of the polyepoxides include, among others,1,4-bis(2,3-epoxypropoxy)benzene, 1,3-bis(2,3-epoxypropoxy) benzene,4,4'-bis(2,3-propoxy)diphenyl ether, 1,8- bis(2,3-epoxypropoxy)octane,1,4-bis(2,3-epoxyprop%xy) cyclohexane,4,4'-bis(2-hydroxy-3,4'-epoxybutoxy)dip enyl dirnethylmethane,1,3-bis(4,5-epoxypentoxy) -'5-chlorobenzene,1,4-bis(3,4-epoxybutoxy)-2-chlorocyclohexane,1,3-bis(2-hydroxy-3,4-epoxybutoxy)benzene and 1,4-bis (2-hydroxy-4,5-epoxypentoxy) benzene.

Other examples include the epoxy polyethers of polyhydric phenolsobtained by reacting a polyhydric phenol with a halogen-containingepoxide or dihalohydrin in the presence of an alkaline medium.Polyhydric phenols that can be used for this purpose include, amongothers, resorcinol, catechol, hydroquinone, methyl resorcinol, orpolynuclear phenols, such as 2,2-bis(4-hydroxyphenyl) propane(Bisphenol-A) 2,2-bis(4-hydroxyphenyl)butane, 4,4-dihydroxybenzophenone,bis-(4-hydroxyhpenyl)ethane, 2,2-bis(4-hydroxyphenyl)pentane, and1,5-dihydroxynaphthalene. The halogen-containing epoxides may be furtherexemplified by 3-chloro-l,2-epoxybutane, 3- bromo-1,2-epoxyhexane,3-chloro-1,2-epoxyoctane, and the like.

The monomer products produced by this method from dihydric phenols andepichlorohydrin may be represented by the general formula wherein Rrepresents a divalent hydrocarbon radical of the dihydric phenol. Thepolymeric products will generally not be a single simple molecule butwill be a complex mixture of glycidyl polyethers of the general formulawherein R is a divalent hydrocarbon radical of the dihydric phenol and nis an integer of the series 0, 1, 2, 3, etc. While for any singlemolecule of the polyether n is an integer, the fact that the obtainedpolyether is a mixture of compounds causes the determined value for n tobe an average which is not necessarily zero or a whole number as notedabove.

The aforedescribed preferred glycidyl polyethers of the dihydric phenolsmay be prepared by reacting the required proportions of the dihydricphenol and the epichlorohydrin in an alkaline medium. The desiredalkalinity is. obtained by adding basic substances, such as sodium orpotassium hydroxide, preferably in stoichiometric excess to theepichlorohydrin. The reaction is preferably accomplished at temperatureswithin the range of from 50 C. to 150 C. The heating is continued forseveral hours to effect the reaction and the product is then washed freeof salt and base.

The preparation of some of the glycidyl polyethers of dihydric phenolswill be illustrated below. Unless otherwise specified, parts indicatedare parts by weight.

PREPARATION OF GLYCIDYL POLYETHERS OF DIHYDRIC PHENOLS Polyether A 1 molof bis-phenol was dissolved in mols of epichlorohydrin and 1 to 2% wateradded to the resulting mixture. 5% by weight phenol was added to themixture. The combined mixture was then placed in a kettle provided withheating and cooling means, agitator, distillation condenser andreceiver. The mixture was brought to 80 C. and 2 mols of solid sodiumhydroxide added in small portions. .Sufiicient cooling is applied duringthe addition so that the temperature is maintained at about 95-97 C. andthere is a gentle distillation of epichlorohydrin and water. After thelast addition of sodium hydroxide with the completion of the reaction,the excess epichlorohydrin is removed by vacuum distillation. Aftercompletion of the distillation, the residue is cooled to about 90 C. andabout 300 parts of benzene added. Cooling drops the temperature of themixture to about 40 C. with precipitation of salt from the solution. The0 salt is removed by filtration and the removed salt carefully washedwith about an additional 300 par-ts of benzene to remove polyethertherefrom. The two benzene solutions were combined and distilled toseparate the benzene. When the kettle temperatures reached 125 C.,vacuum is applied and distillation. The resulting product is a liquidcomposition containing glycidyl polyether of bis-phenol having thefollowing properties: Epoxy Value of 0.541 eq./'100 g., color 6(Gardner), chlorine (percent W.) 0.24, viscosity 70 poises.

Polyether B A solution consisting of 11.7 parts of water, 1.22 parts ofsodium hydroxide, and 13.38 parts of 2,2-bis(4-hydroxyphenyl) propanewas prepared by heating the mixture of ingredients to 70 C. and thencooling to 46 C. at which temperature 14.06 parts of epichlorohydrin wasadded While agitating the mixture. After 25 minutes had elapsed, therewas added during an additional minutes time a solution consisting of5.62 parts of sodium hydroxide in 11.7 parts of water. This caused thetemperature. to rise to 63 C. Washing with water at a temperature of C.to C. was started 30 minutes later and continued for 4 /2 hours. Theproduct was dried by heating to a final temperature of 140 C. in =80minutes and cooled rapidly. At room temperature, the product was anextremely viscous semi-solid having a melting point of 27 C. by DurransMercury Method and a molecular weight of 483. The product had an epoxyvalue eq./ 100 Q g. of 0.40. For convenience, this product will bereferred to as Polyether B.

Preferred members of the above-described group of polyepoxides are theglycidyl polyethers of the dihydric phenols, and especially2,2-bis(4-hydroxyphenyl)propane, having'an epoxy equivalency between 1.0and 2.0

and a molecular weight between 250 and 900. Particularly preferred arethose having Durrans Mercur See Chemical Week, vol. 69, page 27, for'novalac resins which resins are obtained by condensing an aldehyde witha polyhydric phenol. A typical member of this class is the epoxy resinfrom formaldehyde 2,2- bis(4-hydroxyphenyl)propane novalac resin.

The polyamides used in the process of the invention comprise thereaction product of an aliphatic or cycloaliphatic polycarboxylicacidcontaining at least 7 carbon atoms and preferably those containingat least seven carbon atoms between the acidic groups, and an aliphaticpolyamine, the resulting product possessing a group reactive with epoxygroups, such as, for example, free amino groups or free carboxyl groups.

Examples of polybasic acid materials used in making these polyamidesinclude, among others, 1,10-decanedioic acid, 1,12-dodecadienedioicacid, 1,20-eicosadienedioic acid, 1,14-tetradecanedioic acid,1,18-octadecanedioic acid and dimerized and trimerized unsaturated fattyacids obtained by heating polymerizing drying oil fatty acids underknown conditions. Normally, this is effected by utilizing the loweraliphatic esters of drying oil esters so as to prevent decarboxylationduring the heating period. During the heating period, dimers and trimersare usually obtained. The process is illustrated in the Industrial andEngineering Chemistry, vol. 38, page 1139 (1946). The structures of theproducts so obtained are believed to be those given in industrialEngineering Chemistry, vol. 33, page 89 (1941). Numerous drying oilacids can be used in preparing the polymerized acids, but the preferredacids are those containing from 16 to 24 carbon atoms, such as, forexample, linoleic acid, linolenic acid, eleostearic acid, and licannicacid, such as may be derived from oils, such as soybean oil, linseedoil, tung oil, perilla, oiticia, cottonseed, corn, tall, sunflower,dehydrated castor oil and the like. The expression polymerizedunsaturated fatty acids as used herein in a generic sense is intended toinclude the polymerized mixture of dimerized acids, trimerized acids,higher polymerized acids as well as small portions of residual monomer.

The aliphatic polyamines used in preparing the polyamides may be anydi-, trior polyamine such as, for example, ethylene diamine, diethylenetriamine, triethylene tetramine, tetraethylene pentamine,1,4-diaminobutane, 1,3 diaminobutane, hexamethylene diamine, 3 (Nisopropylamino)propylamine, and the like. Particularly preferredpolyamines are those containing from 2 to 12 carbon atoms, andespecially those of the formula wherein x is an integer of 0 to 10 and Ris a bivalent hydrocarbon radical containing from 1 to 10 carbon atoms.Coming under special consideration are those polyamines having at least3 atoms intervening between the amine groups principally involved in theamidification reaction. These three atoms may be carbon atoms or heteroatoms, such as nitrogen atoms.

Especially preferred polyamides are those derived from the aliphaticpolyarnides containing no more than 12 carbon atoms and polymeric fattyacids obtained by dimerizing and trimerizing ethylenically unsaturatedfatty acids containing upv to 24 carbon atoms. These preferredpolyarnides have a viscosity between 10 and 1750 poises at 40 C., andpreferably 20 to 250 poises at 40 C. Preferred polyamides also haveamine values between 50 and 450. Amine number is number of milligrams ofKOH equivalent to the free amino groups present in one gram of thepolyamide.

Corning under special'consideration are the fluid poly- .amides producedby the condensation of polymerized linoleic acid with an aliphaticpolyamine, e.g., diethyl- Another group of polyepoxidesthat may be usedin I preparing the emulsions comprises the glycidyl ethers of value210-230, a viscosity of 500450 poises at 40 C., specific gravity of 0.99and Weighing about 8.3 pounds per gram.

The polyamides used in the process of the invention preferably possessat least one and more preferably two or more hydrogen attached to aminonitrogen atoms or carboxyl hydrogen atoms. Such products are obtained bycontrolling the proportion of reactants so that there is always at leastone amino hydrogen or carboxyl group, such as, for example, by using anexcess of the polyamine reactant. A process for making such polyamides(to obtain free amino groups) or an excess of acid (to obtain carboxylgroups) is illustrated in US. 2,450,940 and US. 2,695,908 and so much ofthese patents relative to the preparation of the polyamides isincorporated herein by reference.

Other materials may also be included in the compositions of the presentinvention. Materials which are particularly desirable for use,especially when the coatings are to be applied while the surface isimmersed under water, are those which impart thixotropic properties tothe composition. Examples of these include, among others, silieas,silicates, non-fibrous asbestos, silica aerogels, montmorillonite clayminerals as hentonite and the like. These materials are preferablyfinely divided and preferably have particles of up to 50 microns insize. Particularly preferred materials to be utilized include the finelydivided colloidal materials which swell in the presence of Water, andespecially those having a heat of interaction with the polyepoxide ofless than 300 ergs/sq./cm. These thixotropic materials are preferablyutilized in amounts up to about 10% by weight of the combined mixture,and still more preferably in amounts varying from about 0.1% to byweight.

Other materials to be added also include inert fillers, such as sand,crushed shells, rocks, aluminum powder, iron particles and the like.

Gther materials that may be used in the composition include those whichtend to extend the polyepoxide but do not seriously affect theproperties of the cured product, such as, for example, coal tars,asphalts, road oils, extracts and distillates, middle oil, refined coaltars, pine tars and oil, and the like as well as other types of resinsas phenol-aldehyde resins, phenol-urea resins, polythiopolymercaptans,vinyl resins, polyolefins, synthetic rubbers, and the like and mixturesthereof. Particles of solid resins as particles of nylons, rayons,dacrons, and the like may also be added for strength. These othermaterials are preferably employed in amounts less than 60% by weight ofthe polyepoxide, and more preferably not more than 40% by weight of thepolyepoxide.

Other materials that may be used include pigments, plasticizers,stabilizers, fungicides, insecticides, activators for the cure of theepoxy resins, such as, for example, phenols, amines, acids, salts,thiols, sulfides, and the like, and mixtures thereof. Other types ofcuring agents for the polyepoxides may also be used in combination withthe above-noted polyamides as long as the polyamides make up at least50% by weight of the combined curing agent.

The proportions of the polyepoxide and the polyamide to be used in thecompositions of the invention should be maintained Within controlledranges in order to obtain the above-noted superior results. The amountof the polyamide employed so as to be freely available to dry thesurface, for example, should be at least a 5% stoichiometric excess andnot more than 50% stoichiometric excess in relation to the polyepoxide.As used herein as in the appended claims stoichiometric amount refers tothat amount needed to furnish one amino hydrogen or COOH hydrogen forevery epoxy group to be reacted. Particularly superior results areobtained when the polyamide is employed in from to 40% stoichiometricexcess.

The compositions may be prepared by any suitable method. They may beprepared, for example, by merely mixing the polyepoxide and poiyainidetogether in the above-noted proportions along with any of theabovcdescribed materials, such as tillers, thixotropic agents, pi

ments and the like. It is sometimes desirable to prepare the polyepoxidealong with fillers, thixotropic agents, pigments and the like in aseparate composition and the polyamide in a separate composition alongwith desired fillers, thixotropic materials and pigments, and then mixthe two compositions together just before application is needed. This ispreferred as it gives more time to work with the composition before itsets up to the hard insoluble material.

A preferred method of preparing the compositions is illustrated in theattached drawing and in Example I. In this case, the polyamide curingagent, filler and pigment are combined as Composition A and CompositionB is prepared by mixing the polyepoxide, pigment and filler.Compositions A and B are then mixed in such proportions as to give a 5%to 50% stoichiometric excess of polyamide in relation to thepolyepoxide. The mixing is accomplished at ambient temperature. Theresulting putty-like composition is then applied to the wet surface.

The viscosity of the compositions used in the process of the inventionwill depend upon the viscosities of the polyepoxide and polyamide usedin the mixture and the amount of added fillers and the like added. Ifthicker more putty-like compositions are needed, they may be prepared bythe addition of more fillers or thixotropic agents. In general,putty-like compositions are obtained by adding from 20% to 150% byweight of the polyepoxide and polyamide of the filler materials. On theother hand, if more fluid compositions are needed as for brushing, etc.one may add more fluid polyepoxides, such as, for example, glycidylethers of polyhydric alcohols, diglycidyl ether, polyglycidyl esters oflower acids and the like, until the desired fluidity is obtained.

The above-noted compositions are applied to the waterwetted surface whenthe surface is in contact with any amount of water, e.g., the surfacemay just have a layer of water say several molecules thick, or thesurface may be totally immersed in fresh or saline water. When thesurface is in contact with only a small amount of water, the compositionmay be applied by simply brushing, spraying or otherwise applying thecomposition. However, when the surface is under water and exposed toconsiderable movement of the water, a putty-like material is preparedand applied to the surface as by hand or other suitable techniques so asto force the composition on the surface to be coated and form acontinuous layer thereon.

The thickness of the coating on the surface will depend on the desiredneed of the application. The coating may, for example, vary from just afew mils thickness up to as high or higher than one inch thickness. Theedges of the coatings are preferably feathered down so as to make asecure seal on the surface.

If the surface to be coated has already been corroded or is coated withoils and the like, it is preferred to clean the surface beforeapplication of the coatings of the invention. This may be accomplishedby any suitable means, such as steel brushing, sandblasting, etchingwith acids, cleaning with organic solvents and the like.

After the material has been coated With the desired coating, the coatingis then allowed to set until it has become cured to the insolubleinfusible state, e.g., is insoluble in acetone and does not soften whenheated say to C. The curing takes place at normal temperatures so noexternal steps need be taken to effect cure. Heat, of course, will speedthe cure, and if possible applications, such as heat lamps and the like,might be utilized to speed the setting up of the coating. Under ordinaryapplication conditions, the coating will generally harden by beingallowed to set say in from 4 to 24 hours after mixing.

The process of the invention is particularly adapted for use in theprotection of metal structures disposed offshore and subjected to theaction of an electrolyte, such as sea water, this process including thesteps of mixing a polyepoxide and fil er material which proportions areselected to form a putty-like composition which preferentially wetstreatment of ferruginous metal surfaces.

metal surfaces and becomes substantially rigid in from about 4 to 24hours after mixing, and applying a coating of said putty-likecomposition on surfaces of metal members to be protected, which surfacesare located between the upper level reached by waves and a level atleast one foot below the low-tide water line, by forcing said puttylikecomposition to contact said metal surfaces and form into a continuouslayer along which there is substantially continuous composition-to-metalcontact.

In treating a vertical metal member which extends through the Water lineof an offshore structure, the surfaces of the member to be protected arecleaned from a level as high as the anticipated lapping of the waves, orsplashing of the water, to a level which is at least about a foot belowthe low-tide water line, said cleaned surface being then coated with alayer of the aforesaid selfhardening mixture.

One of the preferred methods of applying the mixture to the structuralmember is to first form a ring of the material or mixture on thestructural member at a point somewhat above the highest point to whichWater may splash, then smearing the material downwardly and uniformly afoot or so below the low-tide water level with the bottom edge of theplastic feathered to the metal member to be protected. The compositionused for this protection of metal structural members is readily moldedin place by-the use of the applicators hands, particularly when thelatter are wet. The application of the subject compositions to complexgeometric structures is easy and readily accomplished by the use oftechniques similar to those employed in applying putty.

As noted, the process of the invention is also particularly adapted foruse in the repairing of defects in surfaces, such as holes, cracks andthe like and optionally placing of a corrosion resistant coating on suchsurfaces at the same time. This is accomplished by preparing thecomposition as noted above and then applying the composition to thedefective surface. If the defects are very fine cracks, and the wetsurfaces are not exposed to -much action of the Water, the compositionmay be of the fluid type so as to fill the cracks and defects. If thecracks are very large and/ or if the action of the water is very strongit may be necessary to employ the composition in the form of a thickputty as described above. After the composition has been applied to thedefect so as to eifect the repair, the surface may then be coated toeffect the direct corrosion prevention. In some cases, in repairing thedefects in the presence of water, it may be desirable to speed cure ofthe composition so as to more efficiently close the crack or hole. Thismay be accomplished by the addition of cure accelerators noted above,such as phenols, thiols and the like. 7

The process of the invention may be used for the coating and/0r repairof any surface. Such surfaces include, among others, wood, cement,plaster, metal, glass and the like. The process is particularly suitedfor use in treating metal surfaces, such as, for example, copper,aluminum, brass and iron surfaces. The process has shown especiallysuperior results when used for the The'surfaces may be in any type ofstructure, such as, for example, pipes, boats, pilings, reactionvessels,structural members of oil well drilling platforms, well jackets,collection platforms and the like.

To illustrate the manner in which the invention may be carried out, thefollowing examples are given. .It is to be understood, however, that theexamples arefor the purpose of illustration and the invention is not tobe regarded as limited to any of the specific materials or conditionsrecited therein.

components together in' the proportions indicated:

1 use of this composition for treatment of off-shore drilling structuresdisposed in the splash zone.

Composition A was prepared by mixing the following components togetherin the proportions shown:

Composition B was prepared by mixing the following components togetherin the proportions shown:

Parts Polyether A 18 Talc 18 Pigment 1 Triphenyl phosphite 1.8

The compositions were mixed together in substantially equal parts byvolume. The resulting composition was a putty-like composition whichcould be easily formed by hand and when allowed to stand set up to ahard tough flexible insoluble infusible material. 7

The above uncured composition was applied by hand to the steel legs ofthe well jacket and the flow line of an offshore drilling platformlocated in ocean water where severe splash zone corrosion was takingplace. The surfaces had been previously scraped and wire brushed toremove most of the rust. The coating was applied to cover the area inthe spray zone, at the splash zone and about one foot below low tidewater level. The composition was applied under the water line byapplying pressure to squeeze the water away from the member andestablish a substantially continuous composition-to-metal contact underthe layer of the coating material. No difliculty was encountered inhaving the coating adhere to the members and the plastic coating wasfully set about 24 hours to form a hard tough and highly distensiblecoating. The wave action was particularly severe during a stormjustafter the application, but this did not disrupt or remove thecoating.

, The coatings on the Well jacket and fiow line were inspected 20 monthsafter application and were found to be in excellent condition. Thecoatings had withstood considerable pressures and because of its greatdistensibility had not chipped or pealed off. The adhesion was excellentand the coatings were providing complete corroslon protection to themembers.

EXAMPLE II (A). This example further illustrates the preparation of acoating composition containing Polyether A and a polyamide of dimerizedlinoleic acid and diethylene, triamine, and the superior properties ofthe composition as a coating for steel pipes in splash zones.

Composition A was, prepared by mixing the following components togetherin the proportions indicated:

. Parts Polyether A 40.4 Triphenyl phosphite 3.7 Cab-O-Sil (thixotropicagent) 47.5 Chrome yellow pigment 3.4

Composition B was prepared by mixing the following Parts Polyamide ofdimerized'linoleic acid and diethylene triamine having anamine value of306 (versamid 125) 42.3 Silica filler 12.7 Cab-O-Sil (thixotropic agent)44.8 Lamp black .2

I 1 Compositions A and B were then mixed together in a weight ratio of1: 1.1. The resulting mixture was a puttylike composition which could beeasily formed by hand. When allowed to set, the mixture set up in 4 to10 hours to form a hard tough flexible insoluble infusible material.

The above uncured composition was applied by hand to a steel pipedisposed in an accelerated splash zone corrosion test apparatus. Thepipe had been previously cleaned by sandblasting and the coating wasapplied by hand under 3% brine solution. The coating remained intactwith no slumping or running and set to form hard tough flexible coatingin 12 to 18 hours. The pipe was retained in the apparatus where it wasexposed to the brine solution under accelerated splash zone conditionsfor seven days. The water was kept at 70 F. for 24 hours and then thetemperature raised to 150 F. to accelerate the test. At the end of7days, the coating demonstrated excellent adhesion, toughness anddistensibility and excellent corrosion protection.

(B) The above experiment was repeated with the exception that the amountof polyamide employed was reduced to the stoichiometric amount. In thiscase, the composition applied to the steel pipe in the acceleratedsplash zone corrosion test had poor adhesion to the pipe and gave littleprotection against corrosion.

(C) The above experiment was also repeated with the exception that theamount of polyamide was changed to 130% excess. In this case also, thecomposition applied to the steel pipe in the accelerated splash zonecorrosion test had poor adhesion to the pipe and gave little protectionagainst corrosion.

EXAMPLE III Example II was repeated with the exception that the amountof polyamide in the coating composition was changed from 16% excess to50% excess. Related results are obtained.

EXAMPLE IV Example II was repeated with the exception that the amount ofpoly-amide in the coating composition was changed to 10% excess. Relatedresults are also obtained.

EXAMPLE V Example II is repeated with the exception that the amount ofpolyamide in the coating composition is changed to 40% excess. Relatedresults are also obtained.

EXAMPLE v1 Example 11 was repeated with the exception that Polyether Awas replaced with an 85-15 mixture of Polyether A and butyl glycidylether. Related results are obtained.

EXAMPLE VII Example II is also repeated with the exception thatPolyether A is replaced with diglycidyl ether of resorcinol. Relatedresults are also obtained.

EXAMPLE VIII EXAMPLE IX Example II is repeated with the exception thatthe polyamide is replaced by a polyamide of eicosanedioic acid andethylene diamine. Related results are obtained.

. EXAMPLE X Composition A was prepared by mixing the followingcomponents in the proportions indicated:

Percent 8515 mixture of Polyether A and butyl glycidyl ether 30Triphenyl phosphite 6 Asbestos 12 Aluminum powder 1O Phythalox amineblue 3 Composition B was prepared by mixing the following components inthe proportions indicated:

Percent Polyamide of dimerized linoleic acid and diethylene triaminehaving an amine value of 306 15 Polyamide of climerized linoleic acidand diethylene triamine having an amine value of 216 15 Aluminum powder10 Yellow pigment 1.7

The two compositions above were mixed together in substantially twoparts of B to 1 part A by volume. The resulting composition was aputty-like composition which could be easily formed by hand and whenallowed to stand set up to a hard tough distensible composition.

The above composition was applied to the steel legs of offshoreproduction platform as shown in Example I. The coating did not slump orrun and set hard under the water to form a hard tough distensiblecoating. Examination of the coating after 14 months indicated thecoating was in excellent condition, had not chipped or marred and hadgiven complete protection against corrosion.

EXAMPLE XI The coating compositions shown in Examples I, II and X areapplied to iron and copper water piping which have water leaking throughsmall holes. The coatings set up in a few hours to seal the holes andfurnish a hard tough flexible corrosion-resistant coating for the pipes.

EXAMPLE XII The coating compositions shown in Examples I, II and X arealso applied to the side of a metal hull of a boat while in the water soas to effect a repair of a small hole therein. A successful patching andcoating of the hole is obtained.

It has also been unexpectedly found that the new compositions areexcellent materials for treating heat exchange tubes, heat exchange tubesheets, heads and the like. The compositions form a strong corrosionresistant coating when applied according to the process of theinvention, In addition, it was surprisingly found that the resultingcoatings inhibit the formation of mineral scale depositions duringoperation of the heat exchanger.

The above is illustrated by the following: A coating compositionprepared as in Example II was applied to wet surfaces of heat exchangertube sheets of a heat exchanger which had been opened for repairs. Thecomposition was applied so as to form a thick coating on the wet metalsurfaces, and the coating allowed to cure. The heat exchanger was thenput back into service. After 18 months of service, the heat exchangerwas again opened for examination. It was noted that the abovenotedcoating had given excellent corrosion resistance to the surfacestreated. In addition, it was noted that a mineral scale deposition hadoccurred on all water-wetted surfaces except the surfaces coated withthe above material. The coating had thus given unexpected resistance tomineral scale deposition. Compositions containing the above-describedpolyepoxides and certain polythiols possess certain of theabovedescribed properties. Such compositions will be covered incontinuation-in-part applications.

I claim as my invention:

1. process for treating water-wetted surfaces which comprises applyingto the wet surface while immersed in watera mixture of a liquidpolyepoxide having more than one vie-epoxy group and from 5% to 50%stoichiometric excess of a polyamide of apolycarboxylic acid containingat least 7 carbon atoms and an aliphatic polyamine, said poly-amidehaving groups reactive with epoxy groups, and allowing the coating toset hard while the coated surface is immersed in water.

2. A process for forming a corrosion-resistant coating on a metalsurface while the surface is immersed in water which comprises applyingto the surface while immersed in water a putty-like mixture of a liquidpolyepoxide containing only carbon, hydrogen and oxygen and having morethan one vie-epoxy group and from to 50% stoichiometric excess of apolyamide of a polycarboxylic acid containing at least 7 carbon atomsand an aliphatic polyamine, said polyamide possessing hydrogen attachedto amino nitrogen, and said polyamide having greater affinity to themetal surface than the Water and functioning so as to displace the waterfrom the surface of the metal and cure the polyepoxide, and thenallowing the mixture to harden under the water.

3. A process as in claim 2 wherein the polyepoxide is a glycidylpolyether of a polyhydric phenol having an epoxy equivalency of morethan 1.0 and a molecular weight between 250 and 900.

4, A process as in claim 2 wherein the polyamide is a reaction productof a polymerized unsaturated fatty acid and an aliphatic polyamine.

5. A process as in claim 2 wherein the putty-like mixture is applied toa steel metal surface.

6. A process as in claim 2 wherein the polyarnide is employed in astoichiometric excess of 5% to 25%.

7. A process as in claim 2 wherein the putty-like mixture contains afinely-divided colloidal silicon-containing material.

8. A process for the protection against corrosion of a corrodible metalstructure disposed off-shore partly below and partly above the waterlevel, which comprises mixing into a putty like resinous composition aliquid glycidyl polyether of a polyhydric phenol having an epoxyequivalency greater than 1.0 and from 5% to 50% stoichiometric excess ofa polyamide of a polymerized unsaturated fatty acid and an aliphaticpolyamine, said polyami-de containing unreacted groups selected from thegroup consisting of amine and carboxyl groups, applying the saidputty-like composition onto the metal surfaces exposed above and belowthe water level by forcing said putty-like composition against the wetmetal surfaces, thereby disposing a layer of the composition in contactwith said surfaces, and causing the formation on the surfaces of a solidcorrosion-protecting coating of the cured, hardened resinous compositionwhile the coated surface remains immersed in water.

9. A process as in claim 8 wherein the polyamide is a reaction productof a polymerized linoleic acid and diethylene triamine.

10. A process as in claim 9 wherein the glycidyl polyether is a glycidylpolyether of 2,2-bis(4-hydroxyphenyl)- propane.

11. A process as in claim 8 wherein the metal surface is a steelsurface. 1

12. A process for the protection'of a structure which is disposedoff-shore in saline water and has generally tubular ferruginous metalstructural members located within a zone partly below and partly abovethe water level, which comprises forming a mixture (1) of a liquidpolyepoxide having more than one Vic-epoxy group, (2) from 5% to 50%stoichiometric excess of a polyamide of a polymerized unsaturated fattyacid and an aliphatic polyamine, said polyamide possessing hydrogenattached to amine nitrogen, and said polyamide having greater affinityto the metal surface than the water and fumetioning so as to displacethe water from the surface of the metal and cure the polyepoxide, and(3) thixotropic material, applying the resulting mixture to theaforedescribed structural members from above to below the water levelwhile the structure immersed in water, and allowing the coating to setto a hard tough flexible insoluble infusible coating while immersed inthe said water. I

13. A process for repairing a defect in a wetted metal surface whichcomprises applying to the surface while immersed in the water acomposition comprising a mixture of (1) a liquid polyepoxide having morethan one Vic-epoxy group, (2) from 5% to 50% stoichiometric excess of apolyamide of a polycarboxylic acid containing at least 7 carbon atomsand an aliphatic polyamine, said polyamide having groups reactive withepoxy groups, and said polyamide having greater aflinity to the metalsurface than the water and functioning so as to displace the water fromthe surface of the metal and cure the polyepoxide and (3) a thixotropicagent, and then allowing the composition to set to a hard tough flexibleplastic material while the coating surface remains immersed in water.

14. A process for forming a corrosion resistance coating on a surfacewhich is located in a body of water and extends above and below thewater line, the portion above the water line being subjected to frequentsplashing of water by Wave action, which comprises applying to the wetsurface above and below the water line a mixture of a liquid polyepoxidehaving more than one Vic-epoxy group and from 5% to 5 0% stoichiometricexcess of a po'lyamide of a polycarboxylic acid containing at least 7carbon atoms and an aliphatic polyamine, said polyamide having groupsreactive with epoxy groups, and allowing the coating to set hard.

References Cited in the file of this patent UNITED STATES PATENTS2,522,469 Sweeney Sept. 12, 1950 2,705,223 Renfrew et al Mar. 29, 19552,829,984 Yaeger Apr. 8, 1958 2,944,036 Floyd et al. July 5, 19602,986,539 Schniepp et a1 May 30, 1961 2,987,492 P-inder June 6, 1961OTHER REFERENCES Proceedings of the International Patent Ofiice Workshopon Information Retrieved, US. Dept. of Commerce, pp. 147 to 154, T223P204.

Lee et al.: Epoxy Resins, McGraw-Hill, 1957, pages 166-172, 148, 204,274-279, TP 986. E6 L4.

Glaser et al.: Coatings Based on Blends of Polyamide arsrd Epoxy Resins,Ofiicial Digest, February 1957, pages 1 9-169.

1. A PROCESS FOR TREATING WATER-WETTED SURFACES WHICH COMPRISES APPLYINGTO THE WET SURFACE WHILE IMMERSED IN WATER A MIXTURE OF A LIQUIDPOLYEPOXIDE HAVING MORE THAN ONE VIC-EPOXY GROUP AND FROM 5% TO 50%STOICHIOMETRIC EXCESS OF A POLYAMIDE OF A POLYCARBOXYLIC ACID CONTAININGAT LEAST 7 CARBON ATOMS AND AN ALIPHATIC POLYAMINE, SAID POLYAMIDEHAVING GROUPS REACTIVE WITH EPOXY GROUPS, AND ALLOWING THE COATING TOSET HARD WHILE THE COATED SURFACE IS IMMERSED IN WATER.